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/* pbkdf2.c
*
* PKCS #5 password-based key derivation function PBKDF2, see RFC 2898.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2012 Simon Josefsson, Niels Möller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "pbkdf2.h"
#include "macros.h"
#include "memxor.h"
#include "nettle-internal.h"
void
pbkdf2 (void *mac_ctx,
nettle_hash_update_func *update,
nettle_hash_digest_func *digest,
unsigned digest_size, unsigned iterations,
unsigned salt_length, const uint8_t *salt,
unsigned length, uint8_t *dst)
{
TMP_DECL(U, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
TMP_DECL(T, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
unsigned i;
assert (iterations > 0);
if (length == 0)
return;
TMP_ALLOC (U, digest_size);
TMP_ALLOC (T, digest_size);
for (i = 1;;
i++, dst += digest_size, length -= digest_size)
{
uint8_t tmp[4];
uint8_t *prev;
unsigned u;
WRITE_UINT32 (tmp, i);
update (mac_ctx, salt_length, salt);
update (mac_ctx, sizeof(tmp), tmp);
digest (mac_ctx, digest_size, T);
prev = T;
for (u = 1; u < iterations; u++, prev = U)
{
update (mac_ctx, digest_size, prev);
digest (mac_ctx, digest_size, U);
memxor (T, U, digest_size);
}
if (length <= digest_size)
{
memcpy (dst, T, length);
return;
}
memcpy (dst, T, digest_size);
}
}
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